How to Fix Intermittent Temperature or Fuel Gauges in Older BMWs

Have An Older BMW With Jumpy Or Intermittent Temperature Or Fuel Gauge?

The engine temperature and the fuel gauges are mounted to the instrument cluster circuit board (The E30 3-series is specifically shown here, but the 3, 5, 6, 7 and 8 series up through the late ’90s and early ’00s have similar issues and are dealt with in a similar way). They are mounted by a single stud that protrudes off the rear of the gauge. The stud goes through the board (in addition to the two contact pins) and a nut secures it. The stud and nut provide the ground circuit, via their contact on a circuit trace on the board. When the nut is tightened, it makes contact with the circuit trace. Over time, the nuts can loosen and oxidation can form on the contacts. Disassembling the gauge from the circuit board, applying DeoxIT contact cleaner and reassembling, will often return the gauge to proper stable operation. This is not the only cause for the dancing, intermittent or inaccurate gauges, but it is the most common.

DeoxIT (click image):

Disassemble the cluster, remove the nut, and pull the gauge from the board. apply a dab of the DeoxIT contact cleaner/enhancer to each contact point and reassemble.

Assure that the nut is secure to the mounting stud and also has a drop of DeoxIT before assembly.

The above photos show a VDO instrument cluster unit. The MotoMeter unit is similar, but the contacts for the pins look slightly different.

If smacking the dash hood sometimes makes a difference in the operation, consider similar issues with all of the plug contacts. However, also add the harness plugs on the outside of the cluster (vehicle to cluster). I do not recall exactly which plug carries the speedo signal, but I had one E30 that I would reach under the dash (lower panel off) and wiggle one of the plugs to make the speedo work. Was either the left side or right side.

If smacking the dash has no effect and checking all of the connections has no affect, you may heave an issue with the sensor, in the rear differential cover. check out the posts below: